Workbook
Introduction to the Subject of Drawing
The history of the emergence of graphic methods of images and drawings
Drawings in Rus' were made by “draftsmen”, a mention of which can be found in the “Pushkar Order” of Ivan IV.
Other images - drawings, were a bird's eye view of the structure.
At the end of the 12th century. In Russia, large-scale images are introduced and dimensions are indicated. In the 18th century, Russian draftsmen and Tsar Peter I himself made drawings using the method of rectangular projections (the founder of the method is the French mathematician and engineer Gaspard Monge). By order of Peter I, the teaching of drawing was introduced in all technical educational institutions.
The entire history of the development of the drawing is inextricably linked with technical progress. Currently, the drawing has become the main document of business communication in science, technology, production, design, and construction.
It is impossible to create and check a machine drawing without knowing the basics of the graphic language. Which you will meet while studying the subject "Drawing"
Types of graphic images
Exercise: label the names of the images.
The concept of GOST standards. Formats. Frame. Drawing lines.
Exercise 1
Graphic work No. 1
"Formats. Frame. Drawing lines"
Examples of work performed
Test tasks for graphic work No. 1
Option #1.
1. What designation according to GOST has a format of size 210x297:
a) A1; b) A2; c) A4?
2. What is the thickness of the dash-dot line if in the drawing the solid main thick line is 0.8 mm:
a) 1mm: b) 0.8 mm: c) 0.3 mm?
______________________________________________________________
Option #2.
Select and underline the correct answers to the questions.
1. Where in the drawing is the main inscription located:
a) in the lower left corner; b) in the lower right corner; c) in the upper right corner?
2. How much should the axial and center lines extend beyond the contour of the image:
a) 3…5 mm; b) 5…10 mm4 c) 10…15 mm?
Option #3.
Select and underline the correct answers to the questions.
1. What arrangement of A4 format is allowed by GOST:
A) vertical; b) horizontal; c) vertical and horizontal?
2. . What is the thickness of a solid thin line if in the drawing the solid main thick line is 1 mm:
a) 0.3 mm: b) 0.8 mm: c) 0.5 mm?
Option number 4.
Select and underline the correct answers to the questions.
1. At what distance from the edges of the sheet is the drawing frame drawn:
a) left, top, right and bottom – 5 mm each; b) left, top and bottom – 10 mm, right – 25 mm; c) left – 20 mm, top, right and bottom – 5 mm each?
2. What type of line are the axial and center lines made in the drawings:
a) a solid thin line; b) dash-dotted line; c) dashed line?
Option #5.
Select and underline the correct answers to the questions.
1. What are the dimensions of the A4 format according to GOST:
a) 297x210 mm; b) 297x420 mm; c) 594x841 mm?
2. Depending on which line the thickness of the drawing lines is selected:
a) dash-dotted line; b) a solid thin line; c) a solid main thick line?
Fonts (GOST 2304-81)
Font types:
Font sizes:
Practical tasks:
Calculations of drawing font parameters
Test tasks
Option #1.
Select and underline the correct answers to the questions.
What value is taken as the font size:
a) the height of a lowercase letter; b) height of capital letter; c) the height of the spaces between the lines?
Option #2.
Select and underline the correct answers to the questions.
What is the height of the capital letter of rift No. 5:
a) 10 mm; b) 7 mm; c) 5 mm; d) 3.5 mm?
Option #3.
Select and underline the correct answers to the questions.
What is the height of lowercase letters that have protruding elements? c, d, b, r, f:
a) the height of the capital letter; b) the height of a lowercase letter; c) greater than the height of the capital letter?
Option number 4.
Select and underline the correct answers to the questions.
Are uppercase and lowercase letters different in writing? A, E, T, G, I:
a) differ; b) do not differ; c) do they differ in the spelling of individual elements?
Option #5.
Select and underline the correct answers to the questions.
What does the height of the numbers of a drawing font correspond to:
a) the height of a lowercase letter; b) the height of the capital letter; c) half the height of a capital letter?
Graphic work No. 2
"Drawing of a flat part"
Cards - tasks
1 option
Option 2
Option 3
Option 4
Geometric constructions
Dividing a circle into 5 and 10 parts
Dividing a circle into 4 and 8 parts
Dividing a circle into 3, 6 and 12 parts
Dividing a segment into 9 parts
Fixing the material
Practical work:
Based on these types, build a third one. Scale 1:1
Option #1
Option No. 2
Option No. 3
Option No. 4
Fixing the material
Write your answers in your workbook:
Option #1
Option No. 2
Practical work No. 3
"Modeling from a drawing."
Directions for use
To make a cardboard model, first cut out its blank. Determine the dimensions of the workpiece from the image of the part (Fig. 58). Mark (outline) the cutouts. Cut them along the outlined contour. Remove the cut out parts and bend the model according to the drawing. To prevent the cardboard from straightening after bending, draw lines on the outside of the bend with some sharp object.
The wire for modeling must be soft and of arbitrary length (10 – 20 mm).
Fixing the material
Option No. 1 Option No. 2
Fixing the material
In your workbook, make a drawing of the part in 3 views. Apply dimensions.
Option No. 3 Option No. 4
Fixing the material
Working with cards
Fixing the material
Using colored pencils, complete the task on the card.
Amount (increasing)
Clipping
Reinforcement task
Oval -
Algorithm for constructing an oval
1. Construct an isometric projection of a square - rhombus ABCD
2. Let us denote the points of intersection of the circle and the square 1 2 3 4
3. From the top of the rhombus (D) draw a straight line to point 4 (3). We obtain segment D4, which will be equal to the radius of the arc R.
4. Let's draw an arc that will connect points 3 and 4.
5. At the intersection of segment B2 and AC, we obtain point O1.
When the segment D4 and AC intersect, we obtain point O2.
6. From the resulting centers O1 and O2 we will draw arcs R1 that will connect points 2 and 3, 4 and 1.
Fixing the material
Complete a technical drawing of the part, two views of which are shown in Fig. 62
Graphic work No. 9
Part sketch and technical drawing
1. What is called sketch?
Fixing the material
Exercise tasks
Practical work No. 7
"Reading Blueprints"
Graphic dictation
“Drawing and technical drawing of a part based on a verbal description”
Option #1
Frame is a combination of two parallelepipeds, of which the smaller one is placed with a larger base in the center of the upper base of the other parallelepiped. A through stepped hole runs vertically through the centers of the parallelepipeds.
The total height of the part is 30 mm.
The height of the lower parallelepiped is 10 mm, length 70 mm, width 50 mm.
The second parallelepiped has a length of 50 mm and a width of 40 mm.
The diameter of the bottom step of the hole is 35 mm, height 10 mm; diameter of the second stage is 20 mm.
Note:
Option No. 2
Support is a rectangular parallelepiped, to the left (smallest) face of which is attached a half-cylinder, which has a common lower base with the parallelepiped. In the center of the upper (largest) face of the parallelepiped, along its long side, there is a prismatic groove. At the base of the part there is a through hole of a prismatic shape. Its axis coincides in the top view with the axis of the groove.
The height of the parallelepiped is 30 mm, length 65 mm, width 40 mm.
Half-cylinder height 15 mm, base R 20 mm.
The width of the prismatic groove is 20 mm, the depth is 15 mm.
Hole width 10 mm, length 60 mm. The hole is located at a distance of 15 mm from the right edge of the support.
Note: When drawing dimensions, consider the part as a whole.
Option No. 3
Frame is a combination of a square prism and a truncated cone, which stands with its large base in the center of the upper base of the prism. A through stepped hole runs along the axis of the cone.
The total height of the part is 65 mm.
The height of the prism is 15 mm, the size of the sides of the base is 70x70 mm.
The height of the cone is 50 mm, the lower base is Ǿ 50 mm, the upper base is Ǿ 30 mm.
The diameter of the lower part of the hole is 25 mm, height 40 mm.
The diameter of the upper part of the hole is 15 mm.
Note: When drawing dimensions, consider the part as a whole.
Option No. 4
Sleeve is a combination of two cylinders with a stepped through hole that runs along the axis of the part.
The total height of the part is 60 mm.
The height of the lower cylinder is 15 mm, the base is Ǿ 70 mm.
The base of the second cylinder is Ǿ 45 mm.
Bottom hole Ǿ 50 mm, height 8 mm.
Upper part of the hole Ǿ 30 mm.
Note: When drawing dimensions, consider the part as a whole.
Option No. 5
Base is a parallelepiped. In the center of the upper (largest) face of the parallelepiped, along its long side, there is a prismatic groove. There are two through cylindrical holes in the groove. The centers of the holes are spaced from the ends of the part at a distance of 25 mm.
The height of the parallelepiped is 30 mm, length 100 mm, width 50 mm.
Groove depth 15 mm, width 30 mm.
Hole diameters 20 mm.
Note: When drawing dimensions, consider the part as a whole.
Option No. 6
Frame It is a cube, along the vertical axis of which there is a through hole: semi-conical at the top, and then turning into a stepped cylindrical one.
Cube edge 60 mm.
The depth of the semi-conical hole is 35 mm, the upper base is 40 mm, the bottom is 20 mm.
The height of the bottom step of the hole is 20 mm, the base is Ǿ 50 mm. The diameter of the middle part of the hole is 20 mm.
Note: When drawing dimensions, consider the part as a whole.
Option No. 7
Support is a combination of a parallelepiped and a truncated cone. The cone with its large base is placed in the center of the upper base of the parallelepiped. In the center of the smaller side faces of the parallelepiped there are two prismatic cutouts. A through hole of cylindrical shape Ǿ 15 mm is drilled along the axis of the cone.
The total height of the part is 60 mm.
The height of the parallelepiped is 15 mm, length 90 mm, width 55 mm.
The diameters of the cone bases are 40 mm (lower) and 30 mm (upper).
The length of the prismatic cutout is 20 mm, width 10 mm.
Note: When drawing dimensions, consider the part as a whole.
Option No. 8
Frame is a hollow rectangular parallelepiped. In the center of the upper and lower base of the body there are two conical bosses. A through hole of cylindrical shape Ǿ 10 mm passes through the centers of the tides.
The total height of the part is 59 mm.
The height of the parallelepiped is 45 mm, length 90 mm, width 40 mm. The thickness of the walls of the parallelepiped is 10 mm.
The height of the cones is 7 mm, the base is Ǿ 30 mm and Ǿ 20 mm.
Note: When drawing dimensions, consider the part as a whole.
Option No. 9
Support is a combination of two cylinders with one common axis. A through hole runs along the axis: at the top it is prismatic in shape with a square base, and then cylindrical in shape.
The total height of the part is 50 mm.
The height of the lower cylinder is 10 mm, the base is Ǿ 70 mm. The diameter of the base of the second cylinder is 30 mm.
The height of the cylindrical hole is 25 mm, the base is Ǿ 24 mm.
The base side of the prismatic hole is 10 mm.
Note: When drawing dimensions, consider the part as a whole.
Test
Graphic work No. 11
“Drawing and visual representation of the part”
Using the axonometric projection, construct a drawing of the part in the required number of views on a scale of 1:1. Add dimensions.
Graphic work No. 10
“Sketch of a part with design elements”
Draw a drawing of a part from which parts have been removed according to the markings applied. The projection direction for constructing the main view is indicated by an arrow.
Graphic work No. 8
“Drawing of a part with transformation of its shape”
General concept of shape transformation. Relationship between drawing and markings
Graphic work
Making a drawing of an object in three views with transforming its shape (by removing part of the object)
Complete the technical drawing of the part, making, instead of the protrusions marked with arrows, notches of the same shape and size in the same place.
Logical thinking task
Topic “Design of drawings”
Crossword "Projection"
1.The point from which the projecting rays emanate during central projection.
2. What is obtained as a result of modeling.
3. Cube face.
4. The image obtained during projection.
5. In this axonometric projection, the axes are located at an angle of 120° to each other.
6. In Greek, this word means “double dimension.”
7. Side view of a person or object.
8. Curve, isometric projection of a circle.
9. The image on the profile projection plane is a view...
Rebus on the topic “View”
Rebus
Crossword "Axonometry"
Vertically:
1. Translated from French as “front view”.
2. The concept in drawing of what the projection of a point or object is obtained on.
3. The boundary between the halves of a symmetrical part in the drawing.
4. Geometric body.
5. Drawing tool.
6. Translated from Latin, “throw, throw forward.”
7. Geometric body.
8. The science of graphic images.
9. Unit of measurement.
10. Translated from Greek as “double dimension”.
11. Translated from French as “side view”.
12. In the drawing, “she” can be thick, thin, wavy, etc.
Technical Dictionary of Drawing
| Term | Definition of a term or concept | |
| Axonometry | ||
| Algorithm | ||
| Analysis of the geometric shape of an object | ||
| Boss | ||
| Shoulder | ||
| Shaft | ||
| Vertex | ||
| View | ||
| Main view | ||
| Additional view | ||
| Local view | ||
| Screw | ||
| Sleeve | ||
| Dimensions | ||
| screw | ||
| Fillet | ||
| Geometric body | ||
| Horizontal | ||
| Ready room | ||
| Edge | ||
| Dividing a circle | ||
| Division of a segment | ||
| Diameter | ||
| ESKD | ||
| Drawing tools | ||
| Tracing paper | ||
| Pencil | ||
| Drawing Layout | ||
| Construction | ||
| Circuit | ||
| Cone | ||
| Pattern curves | ||
| Circular curves | ||
| Pattern | ||
| Rulers | ||
| Line - leader | ||
| Extension line | ||
| Transition line | ||
| Dimensional line | ||
| Solid line | ||
| Dashed line | ||
| Dashed line | ||
| Lyska | ||
| Scale | ||
| Monge method | ||
| Polyhedron | ||
| Polygon | ||
| Modeling | ||
| Main inscription | ||
| Applying dimensions | ||
| Drawing outline | ||
| Break | ||
| Oval | ||
| Ovoid | ||
| Circle | ||
| Circle in axonometric projection | ||
| Ornament | ||
| Axonometric axes | ||
| Axis of rotation | ||
| Projection axis | ||
| Axis of symmetry | ||
| Hole | ||
| Groove | ||
| Keyway | ||
| Parallelepiped | ||
| Pyramid | ||
| Projection plane | ||
| Prism | ||
| Axonometric projections | ||
| Projection | ||
| Isometric rectangular projection | ||
| Frontal dimetric oblique projection | ||
| Projection | ||
| Groove | ||
| Scan | ||
| Size | ||
| Overall dimensions | ||
| Structural dimensions | ||
| Coordinating sizes | ||
| Part element dimensions | ||
| Gap | ||
| Drawing frame | ||
| Edge | ||
| Technical drawing | ||
| Symmetry | ||
| Pairing | ||
| Standard | ||
| Standardization | ||
| Arrows | ||
| Scheme | ||
| Thor | ||
| Mating point | ||
| Protractor | ||
| Squares | ||
| Simplifications and conventions | ||
| Chamfer | ||
| Drawing formats | ||
| Frontal | ||
| Projection center | ||
| Pairing center | ||
| Cylinder | ||
| Compass | ||
| Drawing | ||
| Working drawing | ||
| Drawing | ||
| Dimensional number | ||
| Reading the drawing | ||
| Washer | ||
| Ball | ||
| Slot | ||
| Engraving | ||
| Font | ||
| Hatching Hatching in axonometry | ||
| Ellipse | ||
| Sketch | ||
Workbook
Practical and graphic work on drawing
The notebook was developed by Anna Aleksandrovna Nesterova, teacher of the highest category of drawing and fine art, teacher of the Municipal Budget Educational Institution “Secondary School No. 1 of Lensk”
Introduction to the Subject of Drawing
Materials, accessories, drawing tools.
2.1. The concept of ESKD standards. If each engineer or draftsman executed and designed drawings in his own way, without following the same rules, then such drawings would not be understandable to others. To avoid this, the USSR adopted and operates state standards of the Unified System of Design Documentation (ESKD).
ESKD standards are regulatory documents that establish uniform rules for the implementation and execution of design documents in all industries. Design documents include drawings of parts, assembly drawings, diagrams, some text documents, etc.
Standards are established not only for design documents, but also for certain types of products manufactured by our enterprises. State standards (GOST) are mandatory for all enterprises and individuals.
Each standard is assigned its own number along with the year of its registration.
The standards are revised from time to time. Changes in standards are associated with the development of industry and the improvement of engineering graphics.
For the first time in our country, standards for drawings were introduced in 1928 under the title “Drawings for all types of mechanical engineering.” Later they were replaced with new ones.
2.2. Formats. The main inscription of the drawing. Drawings and other design documents for industry and construction are performed on sheets of certain sizes.
For economical use of paper, ease of storage and use of drawings, the standard establishes certain sheet formats, which are outlined with a thin line. At school you will use a format whose sides measure 297X210 mm. It is designated A4.
Each drawing must have a frame that limits its field (Fig. 18). The frame lines are solid thick basic ones. They are carried out from above, to the right and below at a distance of 5 mm from the outer frame, made by a continuous thin line along which the sheets are cut. On the left side - at a distance of 20 mm from it. This strip is left for filing drawings.
Rice. 18. Design of A4 sheet
On the drawings, the main inscription is placed in the lower right corner (see Fig. 18). Its shape, size and content are established by the standard. On educational school drawings you will make the main inscription in the form of a rectangle with sides 22X145 mm (Fig. 19, a). A sample of the completed title block is shown in Figure 19, b.
Rice. 19. The main inscription of the educational drawing
Production drawings made on A4 sheets are placed only vertically, and the main inscription on them is only along the short side. On drawings of other formats, the title block can be placed along both the long and short sides.
As an exception, on educational drawings in A4 format, the main inscription is allowed to be placed both along the long and short sides of the sheet.
Before starting the drawing, the sheet is applied to the drawing board. To do this, attach it with one button, for example, in the upper left corner. Then a crossbar is placed on the board and the upper edge of the sheet is placed parallel to its edge, as shown in Figure 20. Pressing the sheet of paper to the board, attach it with buttons, first in the lower right corner, and then in the remaining corners.
Rice. 20. Preparing the sheet for work
The frame and columns of the main inscription are made with a solid thick line.
- What are the dimensions of an A4 sheet? At what distance from the outer frame should the drawing frame lines be drawn? Where is the title block placed on the drawing? Name its dimensions. Look at Figure 19 and list what information it contains.
2.3. Lines. When making drawings, lines of various thicknesses and styles are used. Each of them has its own purpose.
Rice. 21. Drawing lines
Figure 21 shows an image of a part called a roller. As you can see, the part drawing contains different lines. In order for the image to be clear to everyone, the state standard establishes the outline of lines and indicates their main purpose for all industrial and construction drawings. In technical and maintenance lessons you have already used various lines. Let's remember them.
In conclusion, the thickness of lines of the same type should be the same for all images in a given drawing.
Information about the drawing lines is given on the first flyleaf.
- What is the purpose of a solid thick main line?
- Which line is called a dashed line? Where is it used? How thick is this line?
- Where is the dash-dotted thin line used in the drawing? What is its thickness?
- In what cases is a solid thin line used in a drawing? How thick should it be?
- Which line shows the fold line on a development?
In Figure 23 you see an image of the part. Various lines are marked on it with numbers 1,2, etc. Make a table based on this example in your workbook and fill it out.
Rice. 23. Exercise task
Graphic work No. 1
Prepare a sheet of A4 drawing paper. Draw the frame and columns of the main inscription according to the dimensions indicated in Figure 19. Draw various lines, as shown in Figure 24. You can choose another arrangement of groups of lines on the sheet.
Rice. 24. Assignment for graphic work No. 1
The main inscription can be placed both along the short and along the long side of the sheet.
2.4. Drawing fonts. Sizes of letters and numbers of a drawing font. All inscriptions on the drawings must be made in drawing font (Fig. 25). The style of letters and numbers of a drawing font is established by the standard. The standard determines the height and width of letters and numbers, the thickness of stroke lines, the distance between letters, words and lines.
Rice. 25. Inscriptions on drawings
An example of constructing one of the letters in the auxiliary grid is shown in Figure 26.
Rice. 26. Example of letter construction
The font can be either slanted (about 75°) or without slanting.
The standard sets the following font sizes: 1.8 (not recommended, but allowed); 2.5; 3.5; 5; 7; 10; 14; 20; 28; 40. The size (h) of a font is taken to be the value determined by the height of capital letters in millimeters. The height of the letter is measured perpendicular to the base of the line. The lower elements of the letters D, C, Ш and the upper element of the letter Y are made due to the spaces between the lines.
The thickness (d) of the font line is determined depending on the height of the font. It is equal to 0.1h;. The width (g) of the letter is chosen to be 0.6h or 6d. The width of the letters A, D, ZH, M, F, X, Ts, Ш, Ш, Ъ, ы, У is greater than this value by 1 or 2d (including the lower and upper elements), and the width of the letters Г, 3, С is less by d.
The height of lowercase letters is approximately the same as the height of the next smaller font size. So, the height of lowercase letters of size 10 is 7, size 7 is 5, etc. The upper and lower elements of lowercase letters are made due to the distances between the lines and extend beyond the line in 3d. Most lowercase letters are 5d wide. The width of the letters a, m, c, ъ is 6d, the letters zh, t, f, w, shch, s, yu are 7d, and the letters z, s are 4d.
The distance between letters and numbers in words is taken to be 0.2h or 2d, between words and numbers -0.6h or 6d. The distance between the lower lines of the lines is taken equal to 1.7h or 17d.
The standard also establishes another type of font - type A, narrower than the one just discussed.
The height of letters and numbers in pencil drawings must be at least 3.5 mm.
The layout of the Latin alphabet according to GOST is shown in Figure 27.
Rice. 27. Latin font
How to write in drawing font. It is necessary to draw up drawings with inscriptions carefully. Poorly written inscriptions or carelessly applied digits of different numbers may be misunderstood when reading the drawing.
To learn how to write beautifully in a drawing font, first draw a grid for each letter (Fig. 28). After mastering the skills of writing letters and numbers, you can only draw the top and bottom lines of the line.
Rice. 28. Examples of making inscriptions in drawing font
The outlines of the letters are outlined with thin lines. After making sure that the letters are written correctly, trace them with a soft pencil.
For the letters G, D, I, Ya, L, M, P, T, X, C, Ш, Ш, you can only draw two auxiliary lines at a distance equal to their height A.
For the letters B, V, E, N. R, U, CH, Ъ, И, ь. Between the two horizontal lines, another one should be added in the middle, but which is carried out by their middle elements. And for the letters 3, O, F, Yu, four lines are drawn, where the middle lines indicate the boundaries of the roundings.
To quickly write inscriptions in a drawing font, various stencils are sometimes used. You will fill out the main inscription in 3.5 font, the title of the drawing in 7 or 5 font.
- What is the font size?
- What is the width of capital letters?
- What is the height of size 14 lowercase letters? What is their width?
- Complete several inscriptions in your workbook according to the teacher’s instructions. For example, you can write your last name, first name, and home address.
- Fill in the main inscription on sheet of graphic work No. 1 with the following text: drew (last name), checked (teacher's last name), school, class, drawing No. 1, title of the work “Lines”.
2.5. How to apply dimensions. To determine the size of the depicted product or any part of it, dimensions are applied to the drawing. Dimensions are divided into linear and angular. Linear dimensions characterize the length, width, thickness, height, diameter or radius of the measured part of the product. Angular size characterizes the size of the angle.
Linear dimensions in the drawings are indicated in millimeters, but the unit of measurement is not indicated. Angular dimensions are indicated in degrees, minutes and seconds with the designation of the unit of measurement.
The total number of dimensions in the drawing should be the smallest, but sufficient for the manufacture and control of the product.
The rules for applying dimensions are established by the standard. You already know some of them. Let's remind them.
1. Dimensions in the drawings are indicated by dimensional numbers and dimensional lines. To do this, first draw extension lines perpendicular to the segment, the size of which is indicated (Fig. 29, a). Then, at a distance of at least 10 mm from the contour of the part, draw a dimension line parallel to it. The dimension line is limited on both sides by arrows. What the arrow should be is shown in Figure 29, b. Extension lines extend beyond the ends of the arrows of the dimension line by 1...5 mm. Extension and dimension lines are drawn as a solid thin line. Above the dimension line, closer to its middle, the dimension number is applied.
Rice. 29. Applying linear dimensions
2. If there are several dimension lines parallel to each other in the drawing, then a smaller dimension is applied closer to the image. So, in Figure 29, first dimension 5 is applied, and then 26, so that the extension and dimension lines in the drawing do not intersect. The distance between parallel dimension lines must be at least 7 mm.
3. To indicate the diameter, a special sign is applied in front of the size number - a circle crossed out by a line (Fig. 30). If the dimensional number does not fit inside the circle, it is taken outside the circle, as shown in Figure 30, c and d. The same is done when applying the size of a straight segment (see Figure 29, c).
Rice. 30. Sizing circles
4. To indicate the radius, write the capital Latin letter R in front of the dimension number (Fig. 31, a). The dimension line to indicate the radius is drawn, as a rule, from the center of the arc and ends with an arrow on one side, abutting the point of the arc of the circle.
Rice. 31. Applying dimensions of arcs and angles
5. When indicating the size of an angle, the dimension line is drawn in the form of a circular arc with the center at the vertex of the angle (Fig. 31, b).
6. Before the dimensional number indicating the side of the square element, a “square” sign is applied (Fig. 32). In this case, the height of the sign is equal to the height of the numbers.
Rice. 32. Applying the size of the square
7. If the dimension line is located vertically or obliquely, then the dimension numbers are placed as shown in Figure 29, c; thirty; 31.
8. If a part has several identical elements, then it is recommended to indicate on the drawing the size of only one of them with an indication of the quantity. For example, an entry on the drawing “3 holes. 0 10" means that the part has three identical holes with a diameter of 10 mm.
9. When depicting flat parts in one projection, the thickness of the part is indicated as shown in Figure 29, c. Please note that the dimensional number indicating the thickness of the part is preceded by the Latin small letter 5.
10. It is allowed to indicate the length of the part in a similar way (Fig. 33), but in this case a Latin letter is written before the dimension number l.
Rice. 33. Applying the dimension of the length of the part
- In what units are linear dimensions expressed in mechanical engineering drawings?
- How thick should extension and dimension lines be?
- What distance is left between the outline of the image and the dimension lines? between size lines?
- How are dimensional numbers applied on inclined dimensional lines?
- What signs and letters are placed before the dimensional number when indicating the values of diameters and radii?
Rice. 34. Exercise task
- Draw into your workbook, maintaining the proportions, the image of the part given in Figure 34, enlarging it by 2 times. Apply the required dimensions, indicate the thickness of the part (it is 4 mm).
- Draw circles in your workbook with diameters of 40, 30, 20 and 10 mm. Add their dimensions. Draw circular arcs with radii of 40, 30, 20 and 10 mm and mark the dimensions.
2.6. Scale. In practice, it is necessary to create images of very large parts, for example parts of an airplane, ship, car, and very small ones - parts of a clock mechanism, some instruments, etc. Images of large parts may not fit on sheets of standard format. Small details that are barely visible to the naked eye cannot be drawn in full size using existing drawing tools. Therefore, when drawing large parts, their image is reduced, and small ones are increased in comparison with the actual dimensions.
Scale is the ratio of the linear dimensions of the image of an object to the actual ones. The scale of images and their designation on drawings sets the standard.
Reduction scale - 1:2; 1:2.5; 1:4; 1:5; 1:10, etc.
Natural size - 1:1.
Magnification scale - 2:1; 2.5:1; 4:1; 5:1; 10:1, etc.
The most desirable scale is 1:1. In this case, when creating an image, there is no need to recalculate the dimensions.
The scales are written as follows: M1:1; M1:2; M5:1, etc. If the scale is indicated on the drawing in a specially designated column of the main inscription, then the letter M is not written before the scale designation.
It should be remembered that, no matter what scale the image is made, the dimensions on the drawing are actual, i.e. those that the part should have in kind (Fig. 35).
The angular dimensions do not change when the image is reduced or enlarged.
- What is the scale used for?
- What is scale?
- What are the magnification scales established by the standard? What scale of reduction do you know?
- What do the entries mean: M1:5; M1:1; M10:1?
Rice. 35. Drawing of the gasket, made in various scales
Graphic work No. 2
Flat part drawing
Make drawings of the “Gasket” parts using the existing halves of the images, separated by an axis of symmetry (Fig. 36). Add dimensions, indicate the thickness of the part (5 mm).
Complete the work on an A4 sheet. Image scale 2:1.
Directions for use. Figure 36 shows only half of the image of the part. You need to imagine what the complete part will look like, keeping in mind symmetry, and sketch it on a separate sheet. Then you should proceed to the drawing.
A frame is drawn on an A4 sheet and space is allocated for the main inscription (22X145 mm). The center of the working field of the drawing is determined and the image is constructed from it.
First, draw the axes of symmetry and build a rectangle with thin lines that corresponds to the general shape of the part. After this, images of the rectangular elements of the part are marked.
Rice. 36. Tasks for graphic work No. 2
Having determined the position of the centers of the circle and semicircle, draw them. The dimensions of the elements and overall, i.e., the largest in length and height, dimensions of the part are indicated, and its thickness is indicated.
Outline the drawing with the lines established by the standard: first - circles, then - horizontal and vertical straight lines. Fill out the title block and check the drawing.
Topic: Graphic work No. 2 “Drawing of a flat part”
- Goals and objectives:
Target: To familiarize students with the topic “Drawing of a flat part that is symmetrical with respect to one plane of symmetry.”
Tasks: 1 DEVELOPMENTAL : development of creative thinking.
2 EDUCATIONAL: formation of independence, accuracy.
3 EDUCATIONAL: teach how to correctly place parts on a format and apply dimensions to drawings.
- Lesson type: combined.
- Equipment: drawing tools, notebook, textbook, multimedia teaching tables.
- Lesson plan:
- Org. moment.
- Checking homework.
- Theoretical part.
- Practical part.
- House. exercise.
- Lesson summary.
During the classes:
Check of knowledge:
Front work:
1) remember the types of lines and their outline.
2) I ask questions on the topic of sizing.
3) work using cards “Find the error”
Several students work at the board (finish the drawing with the missing lines, construct the 3rd projection based on the 2nd data, correctly apply the dimensions), several students work at their workplaces.
Theoretical part:
Algorithm for constructing a part: APPLICATION (multimedia)
- Analysis of the geometric shape and symmetry of the part.
- Establishing the main type, analyzing its graphic composition, for example: a rectangle, has rectangular cutouts, and a circle in the center. The image is symmetrical about one axis of symmetry.
- Selecting the position of the format: if the length is greater than the height, then – horizontally; if the height is greater than the length, then – vertically.
- Selecting the image scale.
- Defining the working area of the drawing.
- Compositional solution of the drawing:
- drawing a vertical axis of symmetry.
- calculation of the placement of the dimensional rectangle according to the height of the working field using the formula
- construction of an overall rectangle.
- Marking and image construction:
- Clarification of the external outline of the contour of the part.
- Clarification of the internal contour of the part.
- Drawing dimensions along length, height and thickness (overall dimensions)
- Stroke: circles, horizontal lines, vertical, oblique. Filling out the main inscription on the drawing.
Practical part:
Task cards
Homework:
Pages 30-31, Figure 36 (a, b)
Lesson summary:
1. What new did you learn?
2. What practical skills have you consolidated?
3. What new practical skills have you acquired?
4. What did you succeed in the lesson?
5. What else needs to be worked on.
6. Analysis and results, evaluate the work of students.
Preview:
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Slide captions:
Drawing of a “flat” part, symmetrical relative to one plane of symmetry Construction algorithm
1. Analysis of the geometric shape and symmetry of the part.
2. Establishing the main type, analyzing its graphic composition, for example: a rectangle, has rectangular cutouts, and a circle in the center. The image is symmetrical about one axis of symmetry. Circles
3. Selecting the position of the format: if the length is greater than the height, then – horizontally; if the height is greater than the length, then – vertically. 50 120
4. Selecting the image scale. 5. Determination of the working field of the drawing. Working field
6. Compositional solution of the drawing: a. drawing a vertical axis of symmetry. b. calculation of the placement of the overall rectangle along the height of the working field using formula c. construction of an overall rectangle. L slave fields N N h det.
7. Marking and constructing an image: a. clarification of the external outline of the contour of the part. b. clarification of the internal contour of the part.
8. Drawing dimensions in length, height and thickness. S
Stroke: circles, horizontal lines, vertical, oblique. Filling out the title block. S
In Fig. 37 shows an example of a variant of a task for performing calculation and graphic work “Projection Drawing”, as well as a visual image of a given part with a cutout.
The drawing of the part completed according to this task in three projections with correctly sized dimensions is shown in Fig. 38. This example will help students understand their assignment, start doing graphic work and avoid numerous mistakes in its design.
Let us recall that in the task there are only two projections of the part, therefore the dimensions are distributed in two images. However, when preparing a drawing, dimensions should be applied evenly on all three projections.
In conclusion, it should be noted that the number of images of the part (views, sections, sections) should be the smallest, but providing a complete picture of its design when using the established corresponding standards of symbols, signs and inscriptions.
Literature
Popova G.N., Alekseeva S.Yu. Mechanical engineering drawing: Handbook. -L.: Mechanical engineering, Leningrad. department, 1986.
Levitsky V.S. Mechanical engineering drawing. - M.: Higher School, 1988.
Gordon V.O., Sementsov-Ogievsky N.A. Descriptive geometry course. - M.: Nauka, 1994.
Frolov S.A. Descriptive geometry. - M.: Mechanical Engineering, 1978.
Application. Options for assignments for calculation and graphic work
Options for assignments for computational and graphic work on the topic “Projection Drawing” are given in Table. P1. The rules for choosing an assignment option are determined by the teacher.
Table P1. Variants of the assignment for the RGR on the topic “Projection drawing”
|
№ var. |
№ rice. |
A |
b |
With |
№ var. |
№ rice. |
A |
b |
With |
